The present invention relates to an improved motor-glider, and more particularly relates to an improved construction of a glider which is driven for powered flight and take-off by a motorcycle engine and performs power-off gliding with the motorcycle engine being off.
As is well known, gliders are in general roughly classified into three categories, i.e. primary gliders, secondary gliders and high performance gliders. Among others, the high performance gliders, which are also known as soarers, have special aerodynamic characteristics of an extremely high level. The gliders of this category are particularly suited for long distance soaring over a long period of time being carried on the thermals which are usually developed by wind passing over coast slopes, mountain slopes and cliffs, or on thermals developed under cumulonimbi, or on hot thermals developed over big cities and deserts.
In order that a high performance glider should successfuly rise to a level suited for such long distance soaring, it is necessary to tow the glider by an aircraft. In order to attain the level at a training airport ground, it is necessary to tow the glider by an automobile or any other towing equipment such as an winch.
In the hope of avoiding the necessity for such troublesome towing operation, gliders equipped with internal combustion engines, i.e. the so-called motor-gliders, have been lately proposed in the field of this industry and some of the proposed motor-gliders have already been available in the market.
One of the conventional motor-gliders is provided with a propeller power system mounted to the nose cone of the fuselage. However, presence of such a propeller power system at the nose cone of the fuselage more or less detracts from the streamlined outer shape of the glider and tends to cause increased aerodynamic drag on the glider during power-off gliding.
In another one of the conventional motor-gliders, the propeller power system is arranged atop a support which projects above the top of the fuselage during power drive and can be overturned for retraction into the fuselage, just like the retractable landing system, during periods of power-off gliding. Change in the position of the propeller power system, which in general occupys a relatively large share of the total weight of the glider of light construction, naturally causes a corresponding change in the center of gravity of the glider. Such a change in the center of gravity tends to pose significant stability problem regarding the posture of the glider just as power-off gliding is initiated, i.e. during flight without any positive control. In addition, inevitable presence of a gap between the propeller thrust line and the longitudinal axis of the glider amounting to about 1 meter have a delicate, harmful influence upon the glide characteristics of the glider.
Further, in both of the aforementioned types of gliders, the turbulent air generated by motion of the propeller power system flows towards the trailing portion of the glider almost fully shrouding the tail boom and its related parts, thereby applying undesirable aerodynamic drag to the glider.